To start with, you don't need SUM(); SUM(F2-R2) gives exactly the same as
F2-R2.

If you are getting a #VALUE error the cells are presumably not empty, but
contain strings (perhaps just spaces?).
You might want to try
=IF(COUNT(F2,R2)=2,F2-R2,"")
--
David Biddulph

"adriver" wrote in message
...
I am building a log that calculates the amount of time between a doc is
received, and when it is finished with review. When the "date in" and
"date
out" cells are populated, the calculation works fine, but when both cells
are
empty, a #VALUE error is returned, and the boss hates it. Based on a
prior
thread here I've tried
=IF(OR(F2="",R2=""),"",SUM(F2-R2)) but it's not working out.

Please help!